Construction Method for Extendable Assembled Tower Crane Foundation on Soft Soil Layer

Abstract

The present invention belongs to the technical field of underground structure construction, and particularly relates to a construction method for an extendable assembled tower crane foundation on soft soil layers, comprising the following steps: S1, precast pile extension and construction; S2, precast pile grouting; S3, combined installation of the tower crane foundation and the precast piles; S4, installation of the tower crane standard section. The present invention can be directly constructed on soft strata such as backfill soil and silty soil, without the need for large-scale foundation treatment of the site, reducing the construction difficulty, improving the construction efficiency, and solving the problems of long construction period, high cost, and serious resource waste of traditional cast-in-place foundations.

Description

Technical Field

[0001] The present invention belongs to the technical field of underground structure construction, and particularly relates to a construction method for an extendable assembled tower crane foundation on soft soil layers. Background Art

[0002] As a vertical transportation machine in engineering construction, tower cranes are widely used in various projects. However, with the acceleration of the urbanization process, construction land is becoming increasingly tense. During the actual project implementation, more and more tower cranes need to be installed on soft foundations such as backfill soil and silt soil. The traditional tower crane foundation construction technologies mainly include the following four categories: First, according to the bearing capacity of the soft soil layer foundation, the foundation plane size is increased to meet the bearing capacity requirements; second, the soft soil layer is excavated and replaced, or the elevation of the tower crane foundation is lowered to the original soil layer; third, a combined scheme of pile foundation and cast-in-situ concrete foundation is adopted; fourth, the soil layer is grouted and reinforced.

[0003] However, traditional tower crane foundations mostly adopt cast-in-situ concrete structures, which have significant disadvantages such as large foundation volume, long construction period, and high project cost. In the application of pile foundations, traditional pile foundations mainly use cast-in-place piles or precast pipe piles: The construction technology of cast-in-place piles is complex, the early bearing capacity is insufficient, a certain curing period is required, the construction period is long, and the cost is high; the precast piles are long and heavy, inconvenient for transportation and construction, and the precast piles are not provided with grouting holes, relying only on skin friction or end bearing of the piles, and the economy is poor.

[0004] Chinese Patent CN118187132A discloses a construction method for a tower crane concrete foundation based on a natural foundation of soft soil layers, including tower crane foundation site selection, geological soil layer analysis, determination of triaxial deep mixing pile soil reinforcement parameters, construction of triaxial deep mixing pile reinforced soil, earth excavation, tower crane foundation construction, foundation slab construction, tower crane installation, and tower crane monitoring and testing. This patent meets the bearing capacity requirements of the tower crane foundation, breaks through the original condition restrictions of choosing natural foundations for fixed foundations, and expands the use range of fixed foundations. However, this patent adopts an overall foundation reinforcement process. After the construction of triaxial mixing piles, multiple processes such as earth excavation, steel bar binding, and formwork erection are required, the construction period is long, and the reinforcement range needs to cover a certain area around the tower crane foundation. For deep soft soil layers, large-area deep reinforcement is required, and the input of materials such as cement is large, and the economy is poor. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a construction method for an extendable assembled tower crane foundation on soft soil layers, which can directly construct the tower crane foundation on the soft soil layer without earth excavation and replacement, while shortening the construction period and reducing material consumption.

[0006] To solve the above problems, the technical solution of the present invention is as follows:

[0007] A construction method for an extendable assembled tower crane foundation on soft soil layers, comprising the following steps:

[0008] S1. Prefabricated pile extension and construction

[0009] According to the thickness of the soft soil layer and the depth of the bearing stratum, determine the total length of the prefabricated pile. The prefabricated pile includes a first section pile, standard piles, and a last section pile. According to the total length of the prefabricated pile, determine the length of the first section pile, the length of the standard piles, and the length of the last section pile;

[0010] Threaded interfaces are provided at the tops of the first section pile and the standard piles, and access holes are provided on the side walls of the standard piles and the last section pile;

[0011] Use static pressure equipment to press the first section pile into the soft soil layer;

[0012] Carry the standard pile above the first section pile, align it with the threaded interface of the first section pile, insert the connection handle into the access hole of the standard pile to form a force application fulcrum, and rotate the standard pile to threadedly engage and extend it with the first section pile. After extension, use static pressure equipment to press the standard pile into the soft soil layer;

[0013] Carry the last section pile above the standard pile, align it with the threaded interface of the standard pile, insert the connection handle into the access hole of the last section pile to form a force application fulcrum, and rotate the last section pile to threadedly engage and extend it with the standard pile. After extension, use static pressure equipment to press the last section pile into the soft soil layer;

[0014] S2. Grouting of prefabricated piles

[0015] A number of slurry outlet holes are provided on the prefabricated pile. Grout is injected into the prefabricated pile, and the slurry is injected into the soft soil layer around the prefabricated pile through the slurry outlet holes;

[0016] S3. Combined installation of tower crane foundation and prefabricated piles

[0017] A cavity is provided on the tower crane foundation to cooperate with the prefabricated pile. After the slurry hardens, hoist the tower crane foundation into place so that the top of the prefabricated pile penetrates into the cavity, and pour grouting material into the cavity;

[0018] S4. Installation of tower crane standard sections

[0019] After the grouting material hardens, install the tower crane standard sections.

[0020] Preferably, in step S1, the cross-sectional shape of the prefabricated pile is circular, and the pile diameter of the prefabricated pile is between 100 - 300 mm.

[0021] Preferably, in step S1, the lengths of the first section pile, the standard piles, and the last section pile are all between 2 - 4 m. A conical pile tip is provided at the bottom of the first section pile. The first section pile, the standard piles, and the last section pile are all prefabricated steel members.

[0022] Preferably, in step S1, the cross-section of the access hole is square as a whole, the access holes are symmetrically arranged on both sides of the precast pile, and the connecting handle is arranged in an inverted L shape as a whole.

[0023] Preferably, in step S2, the aperture of the slurry outlet hole is 5 - 10 mm, and the vertical spacing of the slurry outlet holes is 300 - 500 mm.

[0024] Preferably, in step S2, a U-shaped anti-blocking member is arranged in cooperation with the slurry outlet hole.

[0025] Preferably, in step S3, the tower crane foundation is arranged in a cube structure as a whole. The length of the tower crane foundation is between 2 - 2.5 m, the width of the tower crane foundation is between 2 - 2.5 m, and the height of the tower crane foundation is between 0.2 - 0.3 m. The tower crane foundation is a precast concrete component.

[0026] Preferably, in step S3, four cavities are arranged on the tower crane foundation, and a precast pile passes through each cavity. The diameter of a single cavity is 200 - 300 mm larger than the diameter of the precast pile.

[0027] Preferably, in step S3, the top of the precast pile protrudes 100 - 200 mm above the upper surface of the tower crane foundation. Shear resistance protrusions are arranged on the pile body part of the precast pile located in the cavity, and connecting grooves are arranged on the inner wall of the cavity. The grouting material is filled between the connecting grooves and the shear resistance protrusions.

[0028] Preferably, in step S4, a lower connecting part is arranged at the top of the last section of the pile, and an upper connecting part is arranged at the bottom of the tower crane standard section. The lower connecting part and the upper connecting part are fixedly connected by bolts.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] The precast pile is divided into a first section pile, a standard pile, and a last section pile. A conical pile tip is arranged at the bottom end of the first section pile, which is convenient for penetrating the soft soil layer. The standard pile serves as an intermediate connection unit and can be flexibly increased or decreased according to the thickness of the soft soil layer. A lower connecting part is arranged at the top end of the last section pile, providing an interface for the subsequent installation of the tower crane standard section. The first section pile, the standard pile, and the last section pile are all steel components prefabricated in the factory, improving the construction efficiency.

[0031] The first section pile, the standard pile, and the last section pile are quickly screwed and connected through a threaded interface, without complex welding procedures. At the same time, problems such as difficult transportation caused by too long single-section of traditional precast piles and low on-site splicing efficiency are avoided. The operation of lengthening the precast pile is quickly completed in the ground environment, improving the construction convenience.

[0032] The precast pile is provided with slurry outlet holes. Through pressure grouting, the slurry diffuses to the soft soil around the precast pile through the slurry outlet holes, forming a reinforced body for the pile-soil collaborative work, enhancing the side friction resistance of the precast pile, and at the same time improving the mechanical properties of the soft soil, making the combination of the precast pile and the soft soil layer closer, and providing a stable support for the tower crane foundation.

[0033] The tower crane foundation adopts precast concrete components in the factory, avoiding the processes such as formwork erection, steel bar binding and long-time curing required for traditional cast-in-place foundations, and shortening the construction period.

[0034] The connecting grooves and shear-resistant protrusions in the cavity greatly increase the connection performance between the precast pile and the tower crane foundation, ensuring that the two can bear the load together, being safe and reliable.

[0035] The present invention can be directly constructed on soft soil layers such as backfill soil and silty soil, without large-scale foundation treatment of the site, reducing the construction difficulty, improving the construction efficiency, and solving the problems of long construction period, high cost and serious resource waste of traditional cast-in-place foundations. Brief Description of the Drawings

[0036] Figure 1 is the structural schematic diagram of the present invention;

[0037] Figure 2 is the structural schematic diagram of the precast pile, access hole, U-shaped anti-blocking member, lower connecting member and shear-resistant protrusion in the present invention;

[0038] Figure 3 is the structural schematic diagram of the first section pile and the U-shaped anti-blocking member in the present invention;

[0039] Figure 4 is the structural schematic diagram of the standard pile, U-shaped anti-blocking member and connecting handle in the present invention;

[0040] Figure 5 is the structural schematic diagram of the last section pile, U-shaped anti-blocking member, shear-resistant protrusion, connecting handle and lower connecting member in the present invention;

[0041] Figure 6 is the structural schematic diagram of the tower crane foundation, cavity and connecting groove in the present invention;

[0042] Figure 7 is the structural schematic diagram of the tower crane foundation, cavity, connecting groove, last section pile, U-shaped anti-blocking member, shear-resistant protrusion and lower connecting member in the present invention;

[0043] Figure 8 is the partial structural sectional view of the precast pile, slurry outlet hole and U-shaped anti-blocking member in the present invention;

[0044] In the figure:

[0045] 1. Prefabricated pile; 101. First section pile; 102. Standard pile; 103. Last section pile; 2. Access hole; 3. Connection handle; 4. Grout outlet hole; 5. Tower crane foundation; 6. Cavity; 7. Lower connector; 8. Tower crane standard section; 9. Upper connector; 10. U-shaped anti-blocking part; 11. Shear resistance protrusion; 12. Connection groove. Detailed implementation mode

[0046] The present invention will be specifically described and explained below in conjunction with embodiments.

[0047] Embodiment 1

[0048] As Figure 1-8 shown, the construction method of the extendable assembled tower crane foundation on soft soil layer described in this embodiment includes the following steps:

[0049] S1. Extension and construction of prefabricated pile 1

[0050] According to the thickness of the soft soil layer and the depth of the bearing stratum, determine the total length of the prefabricated pile 1. The prefabricated pile 1 includes a first section pile 101, a standard pile 102 and a last section pile 103. According to the total length of the prefabricated pile 1, determine the lengths of the first section pile 101, the standard pile 102 and the last section pile 103;

[0051] Threaded interfaces are provided at the tops of both the first section pile 101 and the standard pile 102, and access holes 2 are provided on the side walls of both the standard pile 102 and the last section pile 103;

[0052] Press the first section pile 101 into the soft soil layer;

[0053] Carry the standard pile 102 above the first section pile 101, align it with the threaded interface of the first section pile 101, insert the connection handle 3 into the access hole 2 of the standard pile 102, and rotate the standard pile 102 to threadedly engage and extend it with the first section pile 101. After extension, press the standard pile 102 into the soft soil layer;

[0054] Carry the last section pile 103 above the standard pile 102, align it with the threaded interface of the standard pile 102, insert the connection handle 3 into the access hole 2 of the last section pile 103, and rotate the last section pile 103 to threadedly engage and extend it with the standard pile 102. After extension, press the last section pile 103 into the soft soil layer;

[0055] S2. Grouting of prefabricated pile 1

[0056] A number of grout outlet holes 4 are provided on the prefabricated pile 1. Grout is injected into the prefabricated pile 1, and the grout is injected into the soft soil layer around the prefabricated pile 1 through the grout outlet holes 4;

[0057] S3. Combined installation of tower crane foundation 5 and prefabricated pile 1

[0058] A cavity 6 is provided on the tower crane foundation 5. After the grout hardens, the tower crane foundation 5 is hoisted into place, so that the top end of the precast pile 1 penetrates into the cavity 6, and grout is poured into the cavity 6.

[0059] S4. Install the tower crane standard section 8

[0060] After the grout hardens, install the tower crane standard section 8.

[0061] The tower crane foundation 5 is a precast concrete component in the factory, which avoids the processes such as formwork erection, steel bar binding and long-term curing required for traditional cast-in-situ foundations, and improves the construction efficiency; the first section pile 101, the standard pile 102 and the last section pile 103 are quickly screwed and connected through threaded interfaces, and the number of standard piles 102 can be flexibly adjusted according to the thickness of the soft soil layer and the depth of the bearing stratum, avoiding the problems of design redundancy or insufficient bearing capacity caused by too long single sections in traditional pile foundations, and improving the construction convenience; through pressure grouting, the grout diffuses to the soft soil around the precast pile 1 through the grout outlet holes 4, forming a reinforced body for the pile-soil to work together, without large-area foundation replacement or deep reinforcement, reducing material consumption. At the same time, the ground extension operation is suitable for construction in narrow sites or complex terrains, significantly improving the economy and reliability of the tower crane equipment foundation construction in soft soil layers.

[0062] In step S1, the cross-sectional shape of the precast pile 1 is circular, and the pile diameter of the precast pile 1 is between 100 and 300 mm. The circular cross-section has strong bending and torsion resistance, ensuring the stability of the precast pile 1 under complex stress states; the pile diameter of the precast pile 1 is between 100 and 300 mm, with a light weight, which is convenient for manual handling or small mechanical hoisting.

[0063] In step S1, the lengths of the first section pile 101, the standard pile 102 and the last section pile 103 are all between 2 and 4 m, a tapered pile tip is provided at the bottom of the first section pile 101, and the first section pile 101, the standard pile 102 and the last section pile 103 are all precast steel components. The lengths of the first section pile 101, the standard pile 102 and the last section pile 103 are all less than 4 m, improving the convenience of transporting the precast pile 1.

[0064] In step S1, the overall cross-section of the access hole 2 is square, the access holes 2 are symmetrically arranged on both sides of the precast pile 1, and the connecting handle 3 is integrally arranged in an inverted L shape. When workers perform the extension operation of the precast pile 1, the connecting handle 3 can be inserted into the access hole 2. Since the access hole 2 and the connecting handle 3 form a stable force application point, workers only need to rely on the connecting handle 3 to easily rotate the precast pile 1 with less effort, improving the extension efficiency. The threaded interface uses high-strength steel. Compared with the possible stress concentration or welding defects in traditional welded connections, threaded connections avoid engineering hidden dangers caused by unstable welding quality.

[0065] In step S2, the aperture of the slurry outlet hole 4 is 5-10 mm, and the vertical spacing of the slurry outlet holes 4 is 300-500 mm. This allows the slurry to uniformly penetrate the soil layer around the precast pile 1, increasing the soil cohesion and enhancing the side friction resistance of the precast pile 1.

[0066] In step S2, a U-shaped anti-blocking member 10 is provided in cooperation with the slurry outlet hole 4. During the static pressing of the precast pile 1 into the soil, the U-shaped anti-blocking member 10 can prevent impurities such as soil and particles in the soft soil layer from entering the slurry outlet hole 4, avoiding blockage of the slurry outlet hole 4 and ensuring that the slurry can be smoothly injected into the surrounding soft soil layer during subsequent grouting. The U-shaped anti-blocking member 10 is arranged in cooperation with the slurry outlet hole 4, which can strengthen the structure of the weak part of the slurry outlet hole 4, improve the shear and bending resistance of the precast pile 1 in the soft soil layer, and reduce the damage of the precast pile 1 caused by stress concentration.

[0067] In step S3, the tower crane foundation 5 is integrally arranged in a cube structure. The length of the tower crane foundation 5 is between 2-2.5 m, the width of the tower crane foundation 5 is between 2-2.5 m, and the height of the tower crane foundation 5 is between 0.2-0.3 m. The tower crane foundation 5 is a precast concrete component.

[0068] In step S3, four cavities 6 are provided on the tower crane foundation 5, and a precast pile 1 passes through each cavity 6. The diameter of a single cavity 6 is 200-300 mm larger than the diameter of the precast pile 1. The four precast piles 1 evenly distribute the loads of the tower crane standard section 8 and the tower crane foundation 5.

[0069] In step S3, the top of the precast pile 1 protrudes 100-200 mm above the upper surface of the tower crane foundation 5, providing sufficient vertical installation space for the lower connecting member 7 at the top of the last section pile 103; shear resistance protrusions 11 are provided on the pile body part of the precast pile 1 located in the cavity 6, and connecting grooves 12 are provided on the inner wall of the cavity 6. Grouting material is filled between the connecting grooves 12 and the shear resistance protrusions 11. After the grouting material hardens, it acts together with the shear resistance protrusions 11 and the connecting grooves 12 to fully ensure the load transfer and the safe use of the tower crane standard section 8.

[0070] In step S4, a lower connecting member 7 is provided at the top of the last section pile 103, and an upper connecting member 9 is provided at the bottom of the tower crane standard section 8. The lower connecting member 7 and the upper connecting member 9 are fixedly connected by bolts.

Claims

1. A construction method for an extendable and assembled tower crane foundation on soft soil layers, comprising the following steps: S1. Extension and construction of precast piles (1) According to the thickness of the soft soil layer and the depth of the bearing stratum, determine the total length of the precast piles (1). The precast piles (1) include a first-section pile (101), standard piles (102), and a last-section pile (103). According to the total length of the precast piles (1), determine the lengths of the first-section pile (101), standard piles (102), and last-section pile (103). Threaded interfaces are provided at the tops of both the first-section pile (101) and the standard piles (102), and access holes (2) are provided on the side walls of both the standard piles (102) and the last-section pile (103). Press the first-section pile (101) into the soft soil layer statically. Carry the standard pile (102) above the first-section pile (101), align it with the threaded interface of the first-section pile (101), insert the connecting handle (3) into the access hole (2) of the standard pile (102), and rotate the standard pile (102) to threadedly engage and extend it with the first-section pile (101). After extension, press the standard pile (102) into the soft soil layer statically. Carry the last-section pile (103) above the standard pile (102), align it with the threaded interface of the standard pile (102), insert the connecting handle (3) into the access hole (2) of the last-section pile (103), and rotate the last-section pile (103) to threadedly engage and extend it with the standard pile (102). After extension, press the last-section pile (103) into the soft soil layer statically. S2. Grouting of precast piles (1) A number of slurry outlet holes (4) are provided on the precast piles (1). Grout is injected into the interior of the precast piles (1), and the slurry is injected into the soft soil layer around the precast piles (1) through the slurry outlet holes (4). S3. Combined installation of the tower crane foundation (5) and precast piles (1) A cavity (6) is provided on the tower crane foundation (5). After the slurry hardens, hoist the tower crane foundation (5) into position, so that the top of the precast pile (1) penetrates into the cavity (6), and pour grouting material into the cavity (6). S4. Installation of the tower crane standard section (8) After the grouting material hardens, install the tower crane standard section (8). A tapered pile tip is provided at the bottom of the first-section pile (101). The first-section pile (101), standard piles (102), and last-section pile (103) are all precast steel members. In step S1, the cross-section of the access hole (2) is integrally square, the access holes (2) are symmetrically arranged on both sides of the precast pile (1), and the connecting handle (3) is integrally arranged in an inverted L shape. In step S2, a U-shaped anti-blocking member (10) is arranged in cooperation with the slurry outlet hole (4), which can strengthen the structure of the weak part of the slurry outlet hole (4). Four cavities (6) are provided on the tower crane foundation (5), and each cavity (6) is penetrated by a precast pile (1). In step S3, the top of the precast pile (1) extends 100 - 200 mm above the upper surface of the tower crane foundation (5). Anti-shear protrusions (11) are provided on the pile body part of the precast pile (1) located in the cavity (6), and connecting grooves (12) are provided on the inner wall of the cavity (6). The grouting material is filled between the connecting grooves (12) and the anti-shear protrusions (11). In step S4, a lower connecting member (7) is provided at the top of the end pile (103), and an upper connecting member (9) is provided at the bottom of the tower crane standard section (8). The lower connecting member (7) and the upper connecting member (9) are fixedly connected by bolts.

2. The construction method of the extendable assembled tower crane foundation on soft soil layers according to claim 1, characterized in that, In step S1, the cross-sectional shape of the precast pile (1) is circular, and the pile diameter of the precast pile (1) is between 100 and 300 mm.

3. The construction method of the extendable assembled tower crane foundation on soft soil layers according to claim 1, characterized in that, In step S1, the lengths of the first pile (101), the standard pile (102), and the end pile (103) are all between 2 and 4 m.

4. The construction method of the extendable assembled tower crane foundation on soft soil layers according to claim 1, characterized in that, In step S2, the aperture of the slurry outlet hole (4) is 5-10 mm, and the vertical spacing of the slurry outlet holes (4) is 300-500 mm.

5. The construction method of the extendable assembled tower crane foundation on soft soil layers according to claim 1, characterized in that, In step S3, the tower crane foundation (5) is integrally arranged in a cube structure. The length of the tower crane foundation (5) is between 2 and 2.5 m, the width of the tower crane foundation (5) is between 2 and 2.5 m, the height of the tower crane foundation (5) is between 0.2 and 0.3 m, and the tower crane foundation (5) is a precast concrete member.

6. The construction method of the extendable assembled tower crane foundation on soft soil layers according to claim 1, characterized in that, In step S3, the diameter of a single cavity (6) is 200-300 mm larger than the diameter of the precast pile (1).

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